In a manufacturing process of a semiconductor device, a fine pattern is generally formed using a photolithographic method. In the formation of the fine pattern, multiple transfer masks are usually used. Refinement of a pattern for the semiconductor device requires shortening of a wavelength of an exposure light source used in photolithography, in addition to the refinement of a mask pattern formed in the transfer mask. Nowadays, the exposure light sources used in the manufacture of semiconductor devices are shifting from KrF excimer lasers (wavelength: 248 nm) to ArF excimer lasers (wavelength: 193 nm), that is, shorter wavelength light sources are increasingly used.
The types of transfer masks include a conventional binary mask including a light shielding film pattern made of a chromium-based material on a transparent substrate, and a half tone phase shift mask. A molybdenum silicide (MoSi)-based material is widely used for a phase shift film of the half tone phase shift mask. However, as disclosed in Patent Document 1, it has been discovered recently that the MoSi-based film has a low resistance to exposure light of an ArF excimer laser (that is, so-called ArF light fastness is low). In Patent Document 1, the ArF light fastness is enhanced by subjecting the MoSi-based film after formation of a pattern to the plasma treatment, ultraviolet (UV) light irradiation treatment, or heat treatment to form a passivation film on a surface of the pattern of the MoSi-based film.
Patent Document 2 discloses a defect repairing technique in which a xenon difluoride (XeF2) gas is supplied to a black defect portion of a light shielding film while irradiating the portion with electron beams to etch and remove the black defect portion (the defect repair by irradiation of charged particles such as electron beams as above is hereafter simply referred to as EB defect repair). While the EB defect repair was originally used to correct black defects in an absorber film of a reflective mask for extreme ultraviolet lithography (EUV lithography), it has recently been used for correcting black defects of a MoSi half tone mask as well.
Patent Document 3 discloses the mask structure of a half tone phase shift mask with a high transmittance. Since the conventional phase shift film with a high transmittance formed of a two-layer structure easily thickens, it has the problem that the pattern easily collapses when a fine optical proximity correction (OPC) pattern is formed. The phase shift film of Patent Document 3 is thinner than the phase shift film of a two-layer structure, and thus, the pattern does not easily collapse even if the fine OPC pattern is formed.